Generally, a game parlor has a plurality of game machines and at least one adjustment device to pay out a prize to a player for winning games based on the game result. In recent years, for such game parlors, a system has been proposed in which the score on game machine games is kept on a prepaid card having a data record function and information recorded on the card is read by an adjustment device for managing the game play situation or exchanging the card for a prize based on the information.
However, since the art requires that a player should buy the card to play a game, the player cannot play any game if he or she does not have ready money. If the player spends all his or her ready money, he or she cannot continue playing games although to make a profit, the game parlor wants for him or her to continue playing games if the player can pay a charge.